1. Field of the Invention
The present invention relates to a method and apparatus for polishing chamfers of semiconductor wafers, for polishing chamfers formed on the edges of semiconductor wafers.
2. Background Art
As techniques for etching chamfers formed on the edges of semiconductor wafers such as silicon wafers, CCR (Chemical Corner Rounding) processes are known, but CCR leaves projections at the boundaries between the chamfers and the semiconductor wafer surface. Although these projections are tiny, when the semiconductor wafers are stored in resin cassettes, they can scratch the cassettes and leave small shavings. These shavings can result in degradation of the semiconductor performance.
Aside from CCR, a process of CMP (Chemical Mechanical Polishing) of the chamfers of semiconductor wafers is known. CMP is a technique of polishing using a polishing cloth while supplying polishing fluid to the chamfers of semiconductor wafers. In a conventional apparatus for performing CMP, a polishing drum wound with a polishing cloth is rotatably supported such that the axis thereof is inclined with respect to the rotational axis of the semiconductor wafer, and polishing is performed by pressing this polishing drum against the chamfers of semiconductor wafers while under rotation.
However, even if the above-mentioned CMP apparatus is used, as long as the polishing drum is rotated about an axis which is inclined with respect to the rotational axis of the semiconductor wafer, there is a possibility of ridges being formed on the chamfers of the semiconductor wafers due to polishing in the circumferential direction, thus forming chamfers which are not smooth.